Law & Medicine

‘Time lost is brain lost’


uestion: Which of the following statements regarding “common knowledge” is correct?

Dr. S.Y. Tan, emeritus professor of medicine and former adjunct professor of law at the University of Hawaii, Honolulu

Dr. S.Y. Tan

A. In any negligence action absent common knowledge, expert testimony is then required to prove requisite standard of care and causation.

B. The res ipsa loquitur doctrine, also referred to as the common knowledge rule, exempts the plaintiff from producing an expert witness.

C. An expert is needed in the first place to establish whether something constitutes common knowledge.

D. The jury is the one who determines whether a plaintiff can invoke the common knowledge exception.

E. An example of common knowledge in malpractice law is where a delay in stroke diagnosis results in loss of brain function.

Answer: B. The judge, not the jury or anyone else, makes the decision regarding res ipsa loquitur (the thing speaks for itself) or common knowledge, which exempts a plaintiff from producing an expert witness to testify as to the standard of care and causation. However, this is only true in actions arising out of professional negligence such as medical malpractice, whereas most common negligence actions – for example, slips and falls – do not require expert testimony.

Only a professional, duly qualified by the court as an expert witness, is allowed to offer medical testimony, while the plaintiff will typically be disqualified from playing this role because of the complexity of issues involved unless there is common knowledge. In general, courts are reluctant to grant this exception, which favors the plaintiff.

The best example of res ipsa loquitur is where a surgeon inadvertently leaves behind a sponge or instrument inside a body cavity. Other successfully litigated examples include cardiac arrest in the operating room, hypoxia in the recovery room, burns to the buttock, gangrene after the accidental injection of penicillin into an artery, air trapped subcutaneously from a displaced needle, and a pierced eyeball during a procedure. The factual circumstances of each case are critical to its outcome. For example, in a 2013 New York case, the plaintiff was barred from using the res doctrine.1 The defendant doctor had left a guide wire in the plaintiff’s chest following a biopsy and retrieved it 2 months later. The plaintiff did not call any expert witness, relying instead on the “foreign object” basis for invoking the res doctrine. However, the Court of Appeals reasoned that the object was left behind deliberately, not unintentionally, and that under the circumstances of the case, an expert witness was needed to set out the applicable standard of care, without which a jury could not determine whether the doctor’s professional judgment breached the requisite standard.

The Supreme Court of Kentucky recently rejected the use of common knowledge in a stroke case.2 In 2010, David Shackelford’s rheumatologist referred him to Paul Lewis, MD, an interventional radiologist, for a four-vessel cerebral angiogram to assist with diagnosing the cause of Mr. Shackelford’s chronic headaches. The procedure itself was uneventful, but while in the recovery room, Mr. Shackelford reported a frontal headache and scotoma, which resolved on its own. The headache improved with medication, and the patient experienced no other symptoms. There were no other visual changes, weakness, slurred speech, or facial palsies. Mr. Shackelford was discharged but had to return to the hospital the next morning via ambulance after becoming disoriented at his home. An MRI indicated multiple scattered small infarcts, and he was left with residual short-term memory loss and visual problems.

There was no allegation that the stroke itself was caused by negligence; rather, Mr. Shackelford alleged that the failure to examine and diagnose the stroke after the angiogram was negligent and caused injury greater than that which the stroke would have caused with earlier intervention. To support his claims, Mr. Shackelford’s expert, Michael David Khoury, MD, a vascular surgeon, criticized Dr. Lewis’s failure to examine Mr. Shackelford when his symptoms were consistent with a stroke. However, Dr. Khoury did not opine that Dr. Lewis could have limited the effects of the stroke through earlier intervention. When asked specifically whether he could state within a reasonable degree of medical probability that Dr. Lewis’s postprocedure care was a substantial factor in causing harm to Mr. Shackelford, Dr. Khoury responded that it was “impossible to tell.”

Based largely upon Dr. Khoury’s deposition testimony, the defendants successfully moved for summary judgment on the basis that the expert had failed to opine that the alleged negligence caused any injury to Mr. Shackelford. As a result, Mr. Shackelford could not prove an essential element of his medical malpractice claim. Defense expert Peter J. Pema, MD, a neuroradiologist, acknowledged the general proposition that strokes require timely diagnosis and treatment but did not provide an opinion on causation under the specific facts of this case. Another defense expert, Gregory Postal, MD, opined that Mr. Shackelford began to present symptoms of a stroke after leaving the hospital.

Notwithstanding the lower court’s ruling to summarily dismiss the case, the Court of Appeals found that, in this case, the issue of causation did not require expert medical testimony. It explained that given the ubiquity of information regarding stroke symptom identification and the necessity of prompt treatment, it had become common knowledge that “time lost is brain lost” as to timely medical intervention. In other words, a jury of laymen with this general knowledge could resolve the causation issue without the aid of expert testimony.

However, the Supreme Court of Kentucky held otherwise, writing: “We disagree with the Court of Appeals’ analysis. Although public service campaigns have increased public awareness and knowledge about stroke symptoms and timely intervention, that general information cannot provide the medical expertise necessary to evaluate this particular claim of medical malpractice. In other words, the question is not simply whether ‘time lost is brain lost.’ Rather, the specific facts and circumstances of this case play a significant role in determining whether the alleged negligent conduct was a substantial factor in Shackelford’s injuries, and to what extent. For example, as Dr. Lewis’s deposition testimony illustrates, a variety of factors influenced his diagnosis and treatment of Shackelford, including Shackelford’s medical history and history of cluster headaches; the common side effects of the angiogram procedure, including headache and scotoma; and the manner in which Shackelford’s headache and scotoma presented, as well as their timing. The complexities of these factors and how they affected Dr. Lewis’s evaluation of Shackelford may have also influenced the severity of the injury. These matters are clearly relevant to the determination of an alleged breach of the standard of care. Despite public perception about timely intervention, the average layperson cannot properly weigh such complex medical evidence without the aid of expert opinion. … To conclude otherwise is to drastically expand the res ipsa loquitor exception and to virtually eliminate the need for expert opinion evidence in similar medical malpractice actions that involve common or highly publicized conditions (e.g., stroke, heart attack, and even some cancers).”

Dr. Tan is professor emeritus of medicine and former adjunct professor of law at the University of Hawaii, Honolulu. This article is meant to be educational and does not constitute medical, ethical or legal advice. The author published an earlier version of this topic in the April 19, 2016, issue of Internal Medicine News, available at For additional information, readers may contact the author at


1. James v. Wormuth, 997 N.E.2d 133 (N.Y. 2013).

2. Lewis/Ashland Hospital v. Shackelford, Supreme Court of Kentucky, Opinion of the Court by Justice Keller, rendered August 29, 2019.

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